The Effects of Environmental Toxicology on Daphnia

Topics: Seawater, Heart rate, Water Pages: 8 (2213 words) Published: April 28, 2013
Background information

Daphnia Magna is an arthropod that can grow up to 5 mm. It is a filter feeder meaning it feeds off of suspended particles in the water. Daphnia can consume particles that range from 1µ to 50µ. The heart of Daphnia is located dorsally meaning it's located in the back. The heart rate of Daphnia can range due to many variables, one being temperature. "At a temperature averaging 20o C its heart rate is about 200 beats per minute."2 As the temperature surrounding the Daphnia decreases so does its heart rate. Daphnia has a transparent body which allows one to see its organs. This is why Daphnia is often used in experiments dealing with heart rate. Daphnia inhibits regions of fresh water. They will not survive very long in distilled water or tap water. The reason why they would not survive long in tap water is the amount of chlorine. The amount of chlorine is so high that it would eventually kill the Daphnia. If tap water were ever to be used to host a Daphnia it would have to sit for a period of at least 24 hours in order for the chlorine amount to decrease and therefore become habitable for the Daphnia.


For many years people have used salt during blizzards to uncover rode's for safer driving. What some may not know is the impact road salt can have on the environment and the organisms that live in it. "Road salts can have affects on organisms who inhibit wetlands as far as 550 feet from the roads. "4This is due to the many chemicals as well as dye that road salt contain. Both of these factors impact living things that range from trees to amphibians. When the road salt reaches high enough concentration it becomes highly acidic. As the road salt reaches the grass and soil, the salt is absorbed by the soil and affects many organisms. "In contrast to their tolerance of low oxygen, Daphnia are very sensitive to disturbances of the ionic composition of their environment."5 When Daphnia are exposed to salt after a certain period of time they stop moving and eventually die from these conditions. "Many variables can play in the heart rate of Daphnia as mentioned before. They are extremely sensitive to metal ions like copper and zinc, pesticides, detergents, bleaches and other dissolved toxins. For this reason, they are often used to test waste-water from industry." 6 Although a lot of human products are tested on Daphnia and have affected their heart rate, one cannot assume it will also affect the heart rate of a human. This is because they are two different organisms and have much differences both in the anatomy and the way factors affect the conditions of each organism.

In this lab you will determine the major impacts that road salts can have on the environment and the organisms that live within it. Many of the materials we use in our society harm living organisms and we are not even aware of it. These materials harm organisms because organisms are not adapted to human made materials and are not present in their natural environment. In order to recognize how these materials affect organisms we will analyze the heart rate of Daphnia when exposed to these conditions at different concentrations in contrast to their heart rate during normal conditions. Hypothesis

If the Daphnia is exposed to road salts with higher concentrations then its heart rate will be higher than that of a regular water environment. This is because road salts contain several chemicals as well as dyes that are very harmful to organisms, especially in high concentrations. Also these organisms natural habitats do not contain these chemicals and so their systems have different reactions to them. My null hypothesis is the more NaCl concentration the less heart beats the daphnia will produce per minute.

In this lab the independent variable consist of 10 drops of road salt solutions at a concentration of 5%. This is because the concentrated solutions with road salts will be...
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